Dual mode crystal oscillators used for clock driving circuits, e.g., generally require several gain elements such as transistors, as well as several multiplier and mixer circuits to generate the frequency signals desired. In one suggested system, the oscillator requires at least two transistors, one for oscillating at fundamental, another for oscillating at third harmonic, in addition to mixers and multipliers. This of course, makes large the number of parts needed, increases the cost, power consumption, complexity and adjustment of such circuit to produce the desired output frequencies. Clearly, the possibility of accomplishing the same dual frequency generation, yet while requiring only one transistor and eliminating mixer, multiplier, and post-amplification type circuit elements, would be most useful.